Question

I have a table with a composite Primary Key, arranged something like this:

CREATE TABLE [dbo].[mytable]
(
    [some_id] [smallint] NOT NULL,
    [order_seq] [smallint] NOT NULL,
    -- etc...
)

Both of these columns are part of the primary key (it’s actually a 4-part PK on the real table, but I’ve simplified it for the sake of the example). None of the columns are identities. I’m writing a stored proc that inserts a new record at the next order_seq for a given some_id:

CREATE PROCEDURE some_proc
(
    @some_id smallint,
    @newSeq smallint OUTPUT
)
AS
BEGIN
    insert into mytable (some_id, order_seq)
    values 
    (
         @some_id, 
         (select max(order_seq) + 1 from mytable where some_id = @some_id)
    )

    set @newSeq = /* order_seq of the newly-inserted row */
END

I need to know how to set @newSeq. I’d like to avoid running a select query after the insert, because I don’t want to run into concurrency issues — I’m prohibited from locking the table or using a transaction (don’t ask).

As far as I know, I can’t use SCOPE_IDENTITY() because none of the columns is an identity. How can I set newSeq correctly?

Answer 1

First, if the PK contains four columns, then each insert must include all four columns. Second, you could look into the Output clause if you are using SQL Server 2005+

Declare @NewSeqTable Table( Order_Seq int not null )

Insert MyTable( some_id, order_seq, otherPkCol, otherPkCol2 )
Output inserted.order_seq Into @NewSeqTable
Select @some_id, Max( order_seq ) + 1, otherPkCol, otherPkCol2
From MyTable
Where some_id = @some_id

Select Order_Seq
From @NewSeqTable

OUTPUT Clause (Transact-SQL)